Conference netcad::hub_mgnt

    They can - was there something that made you think otherwise?
    

    Yes, other notes which talked about the 200 node limit in the DECbridge
    90 and how if you put a DECbrouter 90, it might cause the DECbridge 90
    to go into flood mode.
    
    If the DECbrouter 90 implements Spanning Tree, unless I am
    communicating with more than 200 nodes via the DECbrouter 90, should
    the DECbridge 90 stay in non-flood mode?
    

    Doesn't the BRUT support Spanning Tree? If it does, why should more
    than 200 addresses appear at the remote end?
    
        HUB
    ==============
    [DB90 | DBR90]
    		|------------[DBR90]<->[SNA G/W]<->[1500 other systems]
    
    Is there a way to hook this up so there won't be a problem? Can I
    simply attach the DBR90 to the DEChub thinwire port as below?
    
      HUB
    ======
    [DB90]<->[Standalone DBR90]
    			   |----[DBR90]<->[SNA G/W]<->[1500 other systems]
    
    

>    Yes, other notes which talked about the 200 node limit in the DECbridge
>    90 and how if you put a DECbrouter 90, it might cause the DECbridge 90
>    to go into flood mode.

Hmmm... I don't see how this is true, unless you are bridging using the DEC-
brouter 90 to a network with >200 nodes.  If you are routing with the DEC-
brouter 90, it will only count as one node, because when packets are routed, 
they take the address of the router that routes them, so all routed packets
coming from the DECbrouter 90 will appear to come from one address.
   
>    If the DECbrouter 90 implements Spanning Tree, unless I am
>    communicating with more than 200 nodes via the DECbrouter 90, should
>    the DECbridge 90 stay in non-flood mode?
    
The DECbridge 90 will stay in non-flood mode as long as

1) you have less than 199 nodes connected to the rest of your hub and you are
purely routing;
2) you are bridging with the DECbrouter 90 and the sum of the nodes connected
to the workgroup side of the hub plus the nodes on the bridge segment bridged
by the DECbrouter 90 is 199 or less.

Eric

    If the DECbrouter 90 is being used as a bridge, then it will be passing
    (at least) all broadcast packets:
    
    ==================== Hub
      | B |   | B |
      | r |   | r |
      | i |   | o |
      | d |   | u |
      | g |   | t |
      | e |   | e |
      |   |   | r |
      +---+   +---+
        |       |
    backbone    +------> whatever
    
    If 'whatever' brings the total addresses on the hub backplane to over
    200, then you shouldn't use the DECbridge90.
    
    Spanning tree only keeps two or more bridges that connect to the
    same LAN segments from duplicating traffic; if there is more than one
    possible path, Spanning Tree disables paths until there is only one
    possible.  In this case there are 3 segments (backbone, hub, and
    whatever), and the two bridges are not in paralell between any two so
    there is already only one possible path.
     

>    Doesn't the BRUT support Spanning Tree? If it does, why should more
>    than 200 addresses appear at the remote end?

I'm not sure why spanning tree has anything to do with this.  Spanning tree
only turns links on and off. Between the bridge and either the end of the
network or a router, all nodes use their own addresses and hence count toward
the 200 node limit, no matter how many bridges are in between.  (Of course, the
WGB will only count them if they try to talk to nodes beyond it to the back-
bone, so if you have nodes the network that never cross the bridge, they don't
count, but I think that would be a rare occurence.)
        
>    Is there a way to hook this up so there won't be a problem?

Are you bridging or routing?

> Can I simply attach the DBR90 to the DEChub thinwire port as below?
    
>      HUB
>    ======
>    [DB90]<->[Standalone DBR90]
>    			   |----[DBR90]<->[SNA G/W]<->[1500 other systems]

This is functionally equivalent and gains you nothing.  But I don't think there
is a problem with either configuration anyway as long as you route.

If you want to bridge, I recommend connecting the DEWBR to the BACKBONE side,
i.e., to the Ethernet connected to the front of the DEWGB.  This will mean
however that you cannot put the DEWBR into your hub.

Eric Ewanco
DEWBR Engineering

    Is it possible, (I'll post this in the DEWBR conference) to set up a
    mask to allow only the address(es) I'm interested in to be bridged by
    the DECbrouter 90?
    
    I will be using the DECbrouter 90 as a bridge only, not a router.

>    Is it possible, (I'll post this in the DEWBR conference) to set up a
>    mask to allow only the address(es) I'm interested in to be bridged by
>    the DECbrouter 90?

Yes.  That is, it is possible to set up filters.

>    I will be using the DECbrouter 90 as a bridge only, not a router.

Then do you need the DEWGB?  Or do you have a large number of stations off the
hub that you want to bridge as well?

It would generally not be profitable, IMHO, to have two bridges so closely
cascaded like that.  Not only that there is a limit of seven bridges connected
back to back in your network. Just put the DECbrouter 90 on the backbone.

Eric

    The customer doesn't have a real backbone. They have a series of hubs
    on each floor with DECbridge 90FLs in them connected to the main hub
    into a DECrepeater 90FL. This isolates the traffic to each hub. There
    is a DECbridge in each hub so it can be managed via a DECagent 90.
    
    There are two hubs which are seperate backbone connected via Thinwire.
    If I can't put the DECbrouter 90 in the hub, I guess I could connect it
    between the 2 DEChubs in this way?
    
    Does this sound reasonable or do you need more info?

    I think it would be helpfull to have a diagram.

So it sounds like at least one of the hubs either doesn't have a WGB or has a
WGB without a backbone connection.  Why not put the DEWBR in that hub?